1. Field of the Invention
This invention relates to magnesium peroxyacetate and magnesium dihydroperoxide products that can be used to impart antibacterial activity to fibrous substrates.
2. Description of Related Art
Many types of antibacterial agents have been applied to fibrous substrates. However, there are very few agents that retain their germicidal activity after repeated laundering, pose no environmental problems, do not cause undesirable side effects to either the substrate or user thereof, and are inexpensive to manufacture.
Hydrogen peroxide is well known as a safe and effective topical disinfectant and antiseptic that is applied as a dilute aqueous solution to cleanse wounds. However, it has no substantivity to fibrous materials and is readily removed from fabrics or fibrous assemblies by a single wash.
Welch et al., in U.S. Pat. Nos. 4,115,422 and 4,174,418, describe the durable antibacterial effects of water-insoluble complexes of hydrogen peroxide/zirconyl acetate and Danna et al. in U.S. Pat. Nos. 4,172,841 and 4,199,322 describe the durable antibacterial effects of water-insoluble complexes of hydrogen peroxide/zinc acetate. However, each of these systems has several limitations, deficiencies, and disadvantages.
The hydrogen peroxide/magnesium acetate reaction products of the present invention differ from the hydrogen peroxide complexes with zirconyl acetate and zinc acetate of the prior art in terms of their preparation, composition, stability, and application to fibrous substrates.
Zirconyl acetate/hydrogen peroxide complexes require the presence of appreciable amounts of acetic acid in solution for their preparation. Omission of the acetic acid from the preparation process causes exothermic gel formation with concomitant loss of peroxide oxygen or bound peroxide in the complexes. This acetic acid is also requisite for in situ application of the reaction mixture (acetic acid, zirconyl acetate, and hydrogen peroxide) to fibrous substrates in order to obtain suitable amounts of bound peroxide (peroxide oxygen) after appropriate drying and curing.
Other limitations of the zirconyl acetate/hydrogen peroxide complexes of Welch et al. include:
(a) a 24 hour time limitation between preparation of the reaction mixture and its application to fibrous substrates in order to affix antibacterial amounts of peroxide oxygen;
(b) a cure temperature limitation of 140.degree. C. to avoid thermal degradation of the complex; and
(c) the causation of unacceptable weight gains (&gt;15% by wt.), increased fabric stiffness and decreased wettability when obtaining oxygen contents as low as 0.3% on modified fibrous substrates. Such decreased wettability substantially reduces or nullifies the antibacterial activity of the modified fibrous substrates owing to the lack of adequate moisture for transport of the peroxide oxygen to the bacteria.
Similar limitations and disadvantages are observed with the hydrogen peroxide/zinc acetate complexes of Danna et al. and their durable application to fibrous substrates. Effective formation of these complexes likewise requires the presence of acetic acid; this component is also necessary in conjunction with hydrogen peroxide and zinc acetate for in situ application of the complexes to fibrous substrates in a form which provides peroxide oxygen or bound peroxide.
As in the case of the Welch et al.'s hydrogen peroxide/zirconyl acetate complexes, solutions containing Danna et al.'s hydrogen peroxide/zinc acetate complexes rapidly lose their peroxide oxygen available for binding to fibrous substrates if the solutions are not used within 48-72 hours.
Cure temperatures are also limited to a maximum of 140.degree. C. due to irreversible decomposition, which occurs with these and most peroxide species immediately above this threshold.
A further disadvantage for these prior art complexes is that, once formed, their relative insolubility precludes their practical reuse for application to fibrous substrates.
It is also well known that a simple, water-insoluble peroxide of magnesium having the formula MgO.sub.2 can be prepared by adding solid magnesium oxide to a solution of hydrogen peroxide. This product is similar to the starting material (magnesium oxide) in its appearance and physical properties but is not colloidally dispersible in aqueous media (R. E. Hall, Ency. Chem. Tech. Vol. 17, p. 4 (1971)) .